1. Field of the Invention
This invention is in the field of aftermarket vehicle security systems.
2. Description of the Related Art
Many people on occasion inadvertently lock their keys inside their car, and unfortunately, most of these people have not prepared in advance for this problem (such as carrying a spare car key with them). Typically they must then call a tow service to get their door unlocked. This is a major inconvenience, both in time and cost.
A number of solutions have been proposed to solve this problem. These solutions range from simple solutions, such as magnetic key holders that can hold a spare key and can be attached to the underside of the car's body, to sophisticated solutions such as the OnStar® remote car unlocking system, which can send a long distance wireless signal to remotely unlock a car from an OnStar control center, often located hundreds or thousands of miles away.
Some modern automobiles are factory equipped with keyless door locks that respond to fingerprints, directly entered numeric unlocking codes, and voice commands. Other modern automobiles are also factory equipped to directly detect wireless unlocking signals sent from cellular phones as well as from wireless keys and key fobs. However there are millions of automobiles on the road that, while equipped with radio controlled unlocking mechanisms capable of unlocking a car door upon receiving a wireless unlocking command from a electronic key or key fob (RF key or RF key fob), are otherwise unequipped with any ability to unlock the car door if this electronic key is, for example, missing or locked inside the car.
In addition to factory equipped keyless unlocking devices, there also exists an aftermarket of various unlocking devices that can be used to convey keyless unlocking capability to a vehicle that was not originally factory equipped with this capability. These aftermarket devices may either be produced by (or under the control of) one or more vehicle manufacturers or they may be produced by independent manufacturers.
For example, Laroche, In U.S. Pat. No. 6,566,124 describes a knocking activated device with a vibration transducer. This device can be attached to the wiring of a vehicle's electronic lock. The device can store data representative of a sequence of knocks, and generate an electrical output signal, which is directly sent to the vehicles' electronic lock. When the transducer detects this sequence of knocks, the device sends an electrical output signal to the vehicles' electronic lock. A device similar to this concept, called the “Knocklock”, is presently available for sale over the internet from an unknown supplier. However such devices require that the automobile owner make structural modifications to the car, and directly attach the device to the car wiring, and thus tend to be both expensive and difficult to install.
On the other extreme, very simple devices, such as magnetic spare key storage boxes, are often unsatisfactory because a thief may quickly look under the car and locate the spare key. The magnetic spare key storage box can also accidentally become detached from the car due to excessive motion or vibration.